The present invention relates to a new and improved propulsion propeller to propel boats and the like. More particularly, this invention relates to a novel hollow centered spiral propeller which can be formed in one piece and which has pitched surfaces and an open outlet allowing fish and the like to escape without injury.
Propellers used in water for driving boats and the like are well known. Representative examples of such propellers are disclosed in U.S. Pat. Nos. 203,719 and 203,721 to LeRoy Martens. Both of these patents disclose propellers suitable for their intended purpose. However, these two propellers can injure fish and the like as the propeller slices through the water. Also, these prior art propellers tend to develop undesired turbulence as the water rushes around the whirling propeller. Other prior art propellers such as described in U.S. Pat. Nos. 3,426,721 to Justinien and 2,388,711 to Sawyer, rely heavily on a linking particular screw designs with specific boat designs, In addition, in general, the prior art propellers discussed previously lack efficiency and present a danger to sea life. Other patents of interest in this area, which pose similar problems, include U.S. Pat. Nos. 1,459; 30,360; 812,604; 941,923; 1,595,949; 3,070,061; and 3,233,574.